我正在尝试设置一个简单的项目，我使用JPA / Hibernate在REST服务中查询数据库。我的平台是Windows，MySQL 5.6和带有hibernate 4.3的JBoss（Wildfly）8。我的项目设置：
PersonApp（Eclipse Java企业项目）＆gt; PersonApp.ear -PersonData（Eclipse JPA Project）＆gt; PersonData.jar -PersonRest（Eclipse动态Web项目）＆gt; PersonRest.war
PersonData项目包含1个实体类（Person.java），一个用于通过EntityManager（PersonManager.java）执行em.find和em.persist的管理器类，以及persistance.xml
PersonRest项目包含一个REST服务，其中包含一个GET方法，该方法调用PersonManager类来查询所有人员。
PersonApp只是一个容器项目，它包含PersonData和PersonRest作为模块。
现在问题：我将PersonApp.ear部署到Wildfly 8（JBoss），然后在Web浏览器中导航到服务URL。 PersonRest服务调用PersonManager类，它调用Persistence.createEntityManagerFactor（＆＃34; PersonData＆＃34;）;这一行返回＆＃39; null＆＃39;我不明白为什么。
的persistence.xml：
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="PersonData" transaction-type="JTA">
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<jta-data-source>java:jboss/datasources/MySqlDS</jta-data-source>
<class>com.csc.data.Person</class>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>
Wildfly启动输出（显示应用部署，加载数据源，持久性单元）：
14:31:14,607 INFO [org.jboss.modules] (main) JBoss Modules version 1.3.0.Final
14:31:14,841 INFO [org.jboss.msc] (main) JBoss MSC version 1.2.0.Final
14:31:14,919 INFO [org.jboss.as] (MSC service thread 1-6) JBAS015899: WildFly 8.0.0.Final "WildFly" starting
14:31:15,871 INFO [org.jboss.as.server.deployment.scanner] (DeploymentScanner-threads - 1) JBAS015003: Found PersonApp.ear in deployment directory. To trigger deployment create a file called PersonApp.ear.dodeploy
14:31:15,887 INFO [org.jboss.as.server] (Controller Boot Thread) JBAS015888: Creating http management service using socket-binding (management-http)
14:31:15,903 INFO [org.xnio] (MSC service thread 1-8) XNIO version 3.2.0.Final
14:31:15,919 INFO [org.xnio.nio] (MSC service thread 1-8) XNIO NIO Implementation Version 3.2.0.Final
14:31:15,934 INFO [org.jboss.as.clustering.infinispan] (ServerService Thread Pool -- 33) JBAS010280: Activating Infinispan subsystem.
14:31:15,950 INFO [org.jboss.as.security] (ServerService Thread Pool -- 46) JBAS013171: Activating Security Subsystem
14:31:15,966 INFO [org.jboss.as.webservices] (ServerService Thread Pool -- 50) JBAS015537: Activating WebServices Extension
14:31:15,997 INFO [org.wildfly.extension.undertow] (MSC service thread 1-6) JBAS017502: Undertow 1.0.0.Final starting
14:31:15,997 INFO [org.wildfly.extension.undertow] (ServerService Thread Pool -- 49) JBAS017502: Undertow 1.0.0.Final starting
14:31:15,997 INFO [org.jboss.as.security] (MSC service thread 1-2) JBAS013170: Current PicketBox version=4.0.20.Final
14:31:15,997 INFO [org.jboss.as.naming] (ServerService Thread Pool -- 41) JBAS011800: Activating Naming Subsystem
14:31:15,997 INFO [org.jboss.as.jsf] (ServerService Thread Pool -- 39) JBAS012615: Activated the following JSF Implementations: [main]
14:31:16,028 INFO [org.jboss.as.connector.logging] (MSC service thread 1-5) JBAS010408: Starting JCA Subsystem (IronJacamar 1.1.3.Final)
14:31:16,075 INFO [org.jboss.as.naming] (MSC service thread 1-5) JBAS011802: Starting Naming Service
14:31:16,075 INFO [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 28) JBAS010403: Deploying JDBC-compliant driver class org.h2.Driver (version 1.3)
14:31:16,090 INFO [org.jboss.as.mail.extension] (MSC service thread 1-6) JBAS015400: Bound mail session [java:jboss/mail/Default]
14:31:16,106 INFO [org.jboss.as.connector.subsystems.datasources] (ServerService Thread Pool -- 28) JBAS010404: Deploying non-JDBC-compliant driver class com.mysql.jdbc.Driver (version 5.1)
14:31:16,106 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-4) JBAS010417: Started Driver service with driver-name = h2
14:31:16,106 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-4) JBAS010417: Started Driver service with driver-name = com.mysql
14:31:16,184 INFO [org.wildfly.extension.undertow] (ServerService Thread Pool -- 49) JBAS017527: Creating file handler for path C:\wildfly-8.0.0.Final/welcome-content
14:31:16,200 INFO [org.jboss.remoting] (MSC service thread 1-1) JBoss Remoting version 4.0.0.Final
14:31:16,434 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017525: Started server default-server.
14:31:16,543 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017531: Host default-host starting
14:31:16,605 INFO [org.wildfly.extension.undertow] (MSC service thread 1-6) JBAS017519: Undertow HTTP listener default listening on localhost/127.0.0.1:8080
14:31:16,652 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-4) JBAS010400: Bound data source [java:jboss/datasources/MySqlDS]
14:31:16,730 INFO [org.jboss.as.server.deployment] (MSC service thread 1-4) JBAS015876: Starting deployment of "PersonApp.ear" (runtime-name: "PersonApp.ear")
14:31:16,746 INFO [org.jboss.as.server.deployment.scanner] (MSC service thread 1-7) JBAS015012: Started FileSystemDeploymentService for directory C:\wildfly-8.0.0.Final\standalone\deployments
14:31:16,761 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-7) JBAS010400: Bound data source [java:jboss/datasources/ExampleDS]
14:31:16,824 INFO [org.jboss.as.server.deployment] (MSC service thread 1-3) JBAS015876: Starting deployment of "null" (runtime-name: "PersonRest.war")
14:31:16,855 INFO [org.jboss.ws.common.management] (MSC service thread 1-6) JBWS022052: Starting JBoss Web Services - Stack CXF Server 4.2.3.Final
14:31:16,870 INFO [org.jboss.as.jpa] (MSC service thread 1-3) JBAS011401: Read persistence.xml for PersonData
14:31:16,933 INFO [org.jboss.as.jpa] (ServerService Thread Pool -- 52) JBAS011409: Starting Persistence Unit (phase 1 of 2) Service 'PersonApp.ear#PersonData'
14:31:16,948 INFO [org.hibernate.jpa.internal.util.LogHelper] (ServerService Thread Pool -- 52) HHH000204: Processing PersistenceUnitInfo [
name: PersonData
...]
14:31:16,996 INFO [org.hibernate.Version] (ServerService Thread Pool -- 52) HHH000412: Hibernate Core {4.3.1.Final}
14:31:17,012 INFO [org.hibernate.cfg.Environment] (ServerService Thread Pool -- 52) HHH000206: hibernate.properties not found
14:31:17,012 INFO [org.hibernate.cfg.Environment] (ServerService Thread Pool -- 52) HHH000021: Bytecode provider name : javassist
14:31:17,152 INFO [org.jboss.as.jpa] (ServerService Thread Pool -- 52) JBAS011409: Starting Persistence Unit (phase 2 of 2) Service 'PersonApp.ear#PersonData'
14:31:17,277 INFO [org.hibernate.annotations.common.Version] (ServerService Thread Pool -- 52) HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
14:31:17,511 INFO [org.hibernate.dialect.Dialect] (ServerService Thread Pool -- 52) HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
14:31:17,589 INFO [org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory] (ServerService Thread Pool -- 52) HHH000397: Using ASTQueryTranslatorFactory
14:31:17,620 INFO [org.hibernate.validator.internal.util.Version] (ServerService Thread Pool -- 52) HV000001: Hibernate Validator 5.0.3.Final
14:31:17,885 INFO [org.hibernate.tool.hbm2ddl.SchemaExport] (ServerService Thread Pool -- 52) HHH000227: Running hbm2ddl schema export
14:31:17,932 INFO [org.hibernate.tool.hbm2ddl.SchemaExport] (ServerService Thread Pool -- 52) HHH000230: Schema export complete
14:31:18,197 INFO [org.jboss.resteasy.spi.ResteasyDeployment] (MSC service thread 1-2) Deploying javax.ws.rs.core.Application: class com.csc.rest.service.PersonRest
14:31:18,197 INFO [org.jboss.resteasy.spi.ResteasyDeployment] (MSC service thread 1-2) Adding singleton resource com.csc.rest.service.PersonService from Application class com.csc.rest.service.PersonRest
14:31:18,323 INFO [org.wildfly.extension.undertow] (MSC service thread 1-2) JBAS017534: Registered web context: /PersonRest
14:31:18,370 INFO [org.jboss.as.server] (ServerService Thread Pool -- 29) JBAS018559: Deployed "PersonApp.ear" (runtime-name : "PersonApp.ear")
14:31:18,417 INFO [org.jboss.as] (Controller Boot Thread) JBAS015961: Http management interface listening on http://127.0.0.1:9990/management
14:31:18,417 INFO [org.jboss.as] (Controller Boot Thread) JBAS015951: Admin console listening on http://127.0.0.1:9990
14:31:18,417 INFO [org.jboss.as] (Controller Boot Thread) JBAS015874: WildFly 8.0.0.Final "WildFly" started in 4059ms - Started 291 of 351 services (98 services are lazy, passive or on-demand)
REST服务调用上的Wildfly输出：
14:32:06,221 INFO [org.hibernate.jpa.internal.util.LogHelper] (default task-2) HHH000204: Processing PersistenceUnitInfo [
name: PersonData
...]
14:32:06,236 INFO [org.hibernate.dialect.Dialect] (default task-2) HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
14:32:06,236 INFO [org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory] (default task-2) HHH000397: Using ASTQueryTranslatorFactory
14:32:06,252 INFO [org.hibernate.tool.hbm2ddl.SchemaExport] (default task-2) HHH000227: Running hbm2ddl schema export
14:32:06,268 INFO [org.hibernate.tool.hbm2ddl.SchemaExport] (default task-2) HHH000230: Schema export complete
14:32:06,300 ERROR [io.undertow.request] (default task-2) UT005023: Exception handling request to /PersonRest/PersonService: org.jboss.resteasy.spi.UnhandledException: java.lang.NullPointerException
at org.jboss.resteasy.core.ExceptionHandler.handleApplicationException(ExceptionHandler.java:76) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:212) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:149) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:372) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:179) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:220) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51) [resteasy-jaxrs-3.0.6.Final.jar:]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) [jboss-servlet-api_3.1_spec-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:61) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:113) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.security.handlers.AuthenticationCallHandler.handleRequest(AuthenticationCallHandler.java:52) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:45) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:61) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:70) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.security.handlers.SecurityInitialHandler.handleRequest(SecurityInitialHandler.java:76) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:25) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:240) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:227) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:73) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:146) [undertow-servlet-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.server.Connectors.executeRootHandler(Connectors.java:168) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:687) [undertow-core-1.0.0.Final.jar:1.0.0.Final]
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [rt.jar:1.7.0_51]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [rt.jar:1.7.0_51]
at java.lang.Thread.run(Unknown Source) [rt.jar:1.7.0_51]
Caused by: java.lang.NullPointerException
at org.hibernate.engine.transaction.internal.jta.JtaStatusHelper.getStatus(JtaStatusHelper.java:76) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.engine.transaction.internal.jta.JtaStatusHelper.isActive(JtaStatusHelper.java:118) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.engine.transaction.internal.jta.CMTTransaction.join(CMTTransaction.java:149) [hibernate-core-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.joinTransaction(AbstractEntityManagerImpl.java:1602) [hibernate-entitymanager-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.postInit(AbstractEntityManagerImpl.java:210) [hibernate-entitymanager-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.jpa.internal.EntityManagerImpl.<init>(EntityManagerImpl.java:91) [hibernate-entitymanager-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.jpa.internal.EntityManagerFactoryImpl.internalCreateEntityManager(EntityManagerFactoryImpl.java:345) [hibernate-entitymanager-4.3.1.Final.jar:4.3.1.Final]
at org.hibernate.jpa.internal.EntityManagerFactoryImpl.createEntityManager(EntityManagerFactoryImpl.java:313) [hibernate-entitymanager-4.3.1.Final.jar:4.3.1.Final]
at com.csc.data.PersonManager.openConnection(PersonManager.java:51) [PersonData.jar:]
at com.csc.rest.service.PersonService.getAllPersons(PersonService.java:21) [classes:]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [rt.jar:1.7.0_51]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_51]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) [rt.jar:1.7.0_51]
at java.lang.reflect.Method.invoke(Unknown Source) [rt.jar:1.7.0_51]
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:137) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.ResourceMethodInvoker.invokeOnTarget(ResourceMethodInvoker.java:280) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:234) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:221) [resteasy-jaxrs-3.0.6.Final.jar:]
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356) [resteasy-jaxrs-3.0.6.Final.jar:]
... 29 more
看起来Wildfly能够找到persistance.xml，它能够连接到MySQL数据库（它甚至可以按预期删除表数据）。它在输出中显示它找到了持久性单元PersonData。我甚至尝试将提供商更改为某种方式，以确定是否会出错。它确实错误地说它无法找到提供者类。我把它改回来了，错误消失了，所以我认为它能够找到提供者。我错过了什么？
答案 0 :(得分：0)
我找到了解决方案。在我的REST服务中，我自己实例化了PersonManager类。相反，我需要用@Inject注入它。在此之后，它几乎可以工作。然后我遇到了让CDI在RESTeasy REST服务中工作的问题，但这是一个单独的问题。更多详细信息可以在我的JBoss社区主题中找到：https://community.jboss.org/message/863014#863014